EP0518528B1 - Differential pressure control system for variable camshaft timing system - Google Patents

Differential pressure control system for variable camshaft timing system Download PDF

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Publication number
EP0518528B1
EP0518528B1 EP92304883A EP92304883A EP0518528B1 EP 0518528 B1 EP0518528 B1 EP 0518528B1 EP 92304883 A EP92304883 A EP 92304883A EP 92304883 A EP92304883 A EP 92304883A EP 0518528 B1 EP0518528 B1 EP 0518528B1
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EP
European Patent Office
Prior art keywords
hydraulic
valve member
camshaft
control system
operator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92304883A
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German (de)
English (en)
French (fr)
Other versions
EP0518528A1 (en
Inventor
Roger P. Butterfield
Franklin R. Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BorgWarner Inc
BorgWarner Automotive Transmission and Engine Component Corp
Original Assignee
BorgWarner Automotive Transmission and Engine Component Corp
Borg Warner Automotive Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US07/713,465 external-priority patent/US5107804A/en
Application filed by BorgWarner Automotive Transmission and Engine Component Corp, Borg Warner Automotive Inc filed Critical BorgWarner Automotive Transmission and Engine Component Corp
Publication of EP0518528A1 publication Critical patent/EP0518528A1/en
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Publication of EP0518528B1 publication Critical patent/EP0518528B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
    • F16D3/02—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive adapted to specific functions
    • F16D3/10—Couplings with means for varying the angular relationship of two coaxial shafts during motion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/34409—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear by torque-responsive means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • F01L2001/0537—Double overhead camshafts [DOHC]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
    • F01L2001/34423—Details relating to the hydraulic feeding circuit
    • F01L2001/34426—Oil control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
    • F01L2001/34423—Details relating to the hydraulic feeding circuit
    • F01L2001/34426—Oil control valves
    • F01L2001/3443—Solenoid driven oil control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/027—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle four

Definitions

  • This invention relates to an hydraulic control system according to the preamble of claim 1 for controlling the operation of a variable camshaft timing (VCT) system of the type in which the position of the camshaft is circumferentially varied relative to the position of a crankshaft in reaction to torque reversals experienced by the camshaft during its normal operation.
  • VCT variable camshaft timing
  • an hydraulic system is provided to effect the repositioning of the camshaft in reaction to such torque reversals
  • a control system is provided to selectively permit or prevent the hydraulic system from effecting such repositioning.
  • VCT system within the field of the invention in which the system hydraulics include a vane having lobes within an enclosed housing, the vane being oscillatable with respect to the housing, with appropriate hydraulic flow elements to transfer hydraulic fluid within the housing from one side of a lobe to the other, or vice versa, to thereby oscillate the vane with respect to the housing in one direction or the other, an action which is effective to advance or retard the position of the camshaft relative to the crankshaft.
  • Patent 5,002,023 utilizes a control valve in which the exhaustion of hydraulic fluid from one or another of the oppositely acting cylinders is permitted by moving a spool within the valve one way or another from its centered or null position. The movement of the spool occurs in response to an increase or decrease in control hydraulic pressure on an end of the spool and the relationship between the hydraulic force on such end and an oppositely direct mechanical force on the other end which results from a compression spring that acts thereon.
  • a problem with the control system of the aforesaid type is that it relies on an hydraulic force of variable magnitude to counteract a mechanical force.
  • This problem arises from the fact that the pressure and viscosity of the hydraulic fluid that is used in the control system, illustratively engine lubricating oil in an automotive VCT application, can change over a period of time due to changes in the engine r.p.m., the operating temperature or age of the oil, or variations in the composition of the engine oil from time to time as a result of an oil change in which the old oil is replaced by an oil of a different brand or grade.
  • the actual hydraulic control pressure which is at least partly related to viscosity in a dynamic system, is maintained at a predetermined value by changing the duty cycle of a pulse width modulated (PWM) solenoid.
  • PWM pulse width modulated
  • the PWM solenoid which is included in a control system of the aforesaid type, is used to control the hydraulic pressure at a reduced level from a higher pressure source, for example, the engine oil gallery, based on the duration of the "on" cycles of the PWM solenoid relative to its “off” cycles.
  • Very sophisticated software is required to control the duty cycle of a PWM solenoid to prevent changes in engine oil pressure or viscosity from undesirably changing the desired centered or null position of the control valve spool.
  • the present invention provides an improved hydraulic control system according to claim 1. Specifically, the present invention provides an improved apparatus for controlling the position of a spool in an hydraulic control valve in a VCT system, for example, an hydraulic control valve which is used in an oppositely-acting hydraulic cylinder VCT timing system of the type disclosed in the aforesaid US-A-5 002 023, or an hydraulic control valve which is used in a vane-type VCT timing system of the type disclosed in US-A-5 107 804.
  • the control system of the present invention utilizes hydraulic force on both ends of the spool, hydraulic force on one end resulting from directly applied hydraulic fluid from the engine oil gallery at full hydraulic pressure.
  • the hydraulic force on the other end of the spool results from an hydraulic cylinder or other force multiplier which acts thereon in response to system hydraulic fluid at reduced pressure from a PWM solenoid. Because the force at each of the opposed ends of the spool is hydraulic in origin, based on the same hydraulic fluid, changes in pressure or viscosity of the hydraulic fluid will be self-negating, and will not affect the centered or null position of the spool.
  • the force multiplier which acts on the other end of the spool will exactly double the force acting on the one end of the spool, assuming equal hydraulic pressures acting on each.
  • This can be accomplished by providing the hydraulic force multiplier with a piston whose cross-sectional area is exactly double the cross-sectional area of the end of the spool which is acted on directly by system hydraulic pressure. In this way, the hydraulic forces acting on the spool will be exactly in balance when the hydraulic pressure within the force multiplier is exactly equal to one-half that of system hydraulic pressure.
  • This operating condition is achieved with a PWM solenoid duty cycle of 50%, a desirable number because it permits equal increases and decreases in force at the force multiplier end of the spool, to thereby move the spool in one direction or the other by the same amount and at the same rate by increasing or decreasing the duty cycle of the PWM solenoid.
  • a crankshaft 22 has a sprocket 24 keyed thereto, and rotation of the crankshaft 22 during the operation of the engine in which it is incorporated, otherwise not shown, is transmitted to an exhaust camshaft 26, that is, a camshaft which is used to operate the exhaust valves of the engine, by a chain 28 which is trained around the sprocket 24 and a sprocket 30 which is keyed to the camshaft 26.
  • suitable chain tighteners will be provided to ensure that the chain 28 is kept tight and relatively free of slack.
  • the sprocket 30 is twice as large as the sprocket 24. This relationship results in a rotation of the camshaft 26 at a rate of one-half that of the crankshaft 22, which is proper for a 4-cycle engine. It is to be understood that the use of a belt in place of the chain 28 is also contemplated.
  • the camshaft 26 carries another sprocket, namely sprocket 32, Figure 3, 4 and 6, journalled thereon to be oscillatable through a limited arc with respect thereto and to be otherwise rotatable with the camshaft 26.
  • Rotation of the camshaft 26 is transmitted to an intake camshaft 34 by a chain 36 which is trained around the sprocket 32 and a sprocket 38 that is keyed to the intake camshaft 34.
  • the sprockets 32 and 38 are equal in diameter to provide for equivalent rates of rotation between the camshaft 26 and the camshaft 34.
  • the use of a belt in place of the chain 36 is also contemplated.
  • each of the camshafts 26 and 34 is journalled for rotation in bearings 42 and 44, respectively, of the head 50, which is shown fragmentarily and which is bolted to an engine block, otherwise not shown, by bolts 48.
  • the opposite ends of the camshafts 26 and 34, not shown, are similarly journalled for rotation in an opposite end, also not shown, of the head 50.
  • the sprocket 38 is keyed to the camshaft 34 at a location of the camshaft 34 which is outwardly of the head 50.
  • the sprockets 32 and 30 are positioned, in series, on the camshaft 26 at locations outwardly of the head 50, the sprocket 32 being transversely aligned with the sprocket 38 and the sprocket 30 being positioned slightly outwardly of the sprocket 32, to be transversely aligned with the sprocket 24.
  • the sprocket 32 has an arcuate retainer 52 ( Figures 7 and 8) as an integral part thereof, and the retainer 52 extends outwardly from the sprocket 32 through an arcuate opening 30a in the sprocket 30.
  • the sprocket 30 has an arcuate hydraulic body 46 bolted thereto and the hydraulic body 46, which houses certain of the hydraulic components of the associated hydraulic control system, receives and pivotably supports the body end of each of a pair of oppositely acting, single acting hydraulic cylinders 54 and 56 which are positioned on opposite sides of the longitudinal axis of the camshaft 26.
  • the piston ends of the cylinders 54 and 56 are pivotally attached to an arcuate bracket 58, and the bracket 58 is secured to the sprocket 32 by a plurality of threaded fasteners 60.
  • the arcuate position of the sprocket 32 will be changed relative to the sprocket 30, either to advance the sprocket 32 if the cylinder 54 is extended and the cylinder 56 is retracted, which is the operating condition illustrated in Figures 2 and 4, or to retard the sprocket 32 relative to the sprocket 30 if the cylinder 56 is extended and the cylinder 54 is retracted, which is the operating condition illustrated in Figures 1, 3, 7 and 8.
  • the retarding or advancing of the position of the sprocket 32 relative to the position of the sprocket 30, which is selectively permitted or prevented in reaction to the direction of torque in the camshaft 26, as explained in the aforesaid U.S. Patent 5,002,023, will advance or retard the position of the camshaft 34 relative to the position of the camshaft 26 by virtue of the chain drive connection provided by the chain 36 between the sprocket 32, which is journalled for limited relative arcuate movement on the camshaft 26, and the sprocket 38, which is keyed to the camshaft 34.
  • FIGS 10-19 illustrate an embodiment of the present invention in which a housing in the form of a sprocket 132 is oscillatingly journalled on a camshaft 126.
  • the camshaft 126 may be considered to be the only camshaft of a single camshaft engine, either of the overhead camshaft type or the in block camshaft type.
  • the camshaft 126 may be considered to be either the intake valve operating camshaft or the exhaust valve operating camshaft of a dual camshaft engine.
  • the sprocket 132 and the camshaft 126 are rotatable together, and are caused to rotate by the application of torque to the sprocket 132 by an endless roller chain 138, shown fragmentarily, which is trained around the sprocket 132 and also around a crankshaft, not shown.
  • the sprocket 132 is oscillatingly journalled on the camshaft 126 so that it is oscillatable at least through a limited arc with respect to the camshaft 126 during the rotation of the camshaft, an action which will adjust the phase of the camshaft 126 relative to the crankshaft.
  • An annular pumping vane 160 is fixedly positioned on the camshaft 126, the vane 160 having a diametrically opposed pair of radially outwardly projecting lobes 160a, 160b and being attached to an enlarged end portion 126a of the camshaft 126 by bolts 162 which pass through the vane 160 into the end portion 126a.
  • the camshaft 126 is also provided with a thrust shoulder 126b to permit the camshaft to be accurately positioned relative to an associated engine block, not shown.
  • the pumping vane 160 is also precisely positioned relative to the end portion 126a by a dowel pin 164 which extends therebetween.
  • the lobes 160a, 160b are received in radially outwardly projecting recesses 132a, 132b, respectively, of the sprocket 132, the circumferential extent of each of the recesses 132a, 132b being somewhat greater than the circumferential extent of the vane lobe 160a, 160b which is received in such recess to permit limited oscillating movement of the sprocket 132 relative to the vane 160.
  • the recesses 132a, 132b are closed around the lobes 160a, 160b, respectively, by spaced apart, transversely extending annular plates 166, 168 which are fixed relative to the vane 160, and, thus, relative to the camshaft 126, by bolts 170 which extend from one to the other through the same lobe, 160a, 160b. Further, the inside diameter 132c of the sprocket 132 is sealed with respect to the outside diameter of the portion 160d of the vane 160 which is between the lobes 160a, 160b, and the tips of the lobes 160a, 160b of the vane 160 are provided with seal receiving slots 160e, 160f, respectively.
  • each of the recesses 132a, 132b of the sprocket 132 is capable of sustaining hydraulic pressure, and within each recess 132a, 132b, the portion on each side of the lobe 160a, 160b, respectively, is capable of sustaining hydraulic pressure.
  • hydraulic fluid flows into the recesses 132a, 132b by way of a common inlet line 182.
  • the inlet line 182 terminates at a juncture between opposed check valves 184 and 186 which are connected to the recesses 132a, 132b, respectively, by branch lines 188, 190, respectively.
  • the check valves 184, 186 have annular seats 184a, 186a, respectively, to permit the flow of hydraulic fluid through the check valves 184, 186 into the recesses 132a, 132b, respectively.
  • the flow of hydraulic fluid through the check valves 184, 186 is blocked by floating balls 184b, 186b, respectively, which are resiliently urged against the seats 184a, 186a, respectively, by springs 184c, 186c, respectively.
  • the check valves 184, 186 thus, permit the initial filling of the recesses 132a, 132b and provide for a continuous supply of make-up hydraulic fluid to compensate for leakage therefrom.
  • Hydraulic fluid enters the line 182 by way of a spool valve 192, which is incorporated within the camshaft 126, and hydraulic fluid is returned to the spool valve 192 from the recesses 132a, 132b by return lines 194, 196, respectively.
  • the spool valve 192 is made up of a cylindrical member 198 and a spool 200 which is slidable to and fro within the member 198.
  • the spool 200 has cylindrical lands 200a and 200b on opposed ends thereof, and the lands 200a and 200b, which fit snugly within the member 198, are positioned so that the land 200b will block the exit of hydraulic fluid from the return line 196, or the land 200a will block the exit of hydraulic fluid from the return line 194, or the lands 200a and 200b will block the exit of hydraulic fluid from both the return lines 194 and 196, as is shown in Figure 19, where the camshaft 126 is being maintained in a selected intermediate position relative to the crankshaft of the associated engine.
  • the position of the spool 200 within the member 198 is influenced by an opposed pair of springs 202, 204 which act on the ends of the lands 200a, 200b, respectively.
  • the spring 202 resiliently urges the spool 200 to the left, in the orientation illustrated in Figure 19, and the spring 204 resiliently urges the spool 200 to the right in such orientation.
  • the position of the spool 200 within the member 198 is further influenced by a supply of pressurized hydraulic fluid within a portion 198a of the member 198, on the outside of the land 200a, which urges the spool 200 to the left.
  • the portion 198a of the member 198 receives its pressurized fluid (engine oil) directly from the main oil gallery ("MOG") 230 of the engine by way of a conduit 230a, and this oil is also used to lubricate a bearing 232 in which the camshaft 126 of the engine rotates.
  • engine oil pressurized fluid
  • MOG main oil gallery
  • the control of the position of the spool 200 within the member 198 is in response to hydraulic pressure within a control pressure cylinder 234 whose piston 234a bears against an extension 200c of the spool 200.
  • the surface area of the piston 234a is greater than the surface area of the end of the spool 200 which is exposed to hydraulic pressure within the portion 198a, and is preferably twice as great.
  • the hydraulic pressures which act in opposite directions on the spool 200 will be in balance when the pressure within the cylinder 234 is one-half that of the pressure within the portion 198a, assuming that the surface area of the piston 234a is twice that of the end of the land 200a of the spool.
  • the pressure within the cylinder 234 is controlled by a solenoid 206, preferably of the pulse width modulated type (PWM), in response to a control signal from an electronic engine control unit (ECU) 208, shown schematically, which may be of conventional construction.
  • ECU electronic engine control unit
  • the on-off pulses of the solenoid 206 will be of equal duration; by increasing or decreasing the on duration relative to the off duration, the pressure in the cylinder 234 will be increased or decreased relative to such one-half level, thereby moving the spool 200 to the right or to the left, respectively.
  • the solenoid 206 receives engine oil from the engine oil gallery 230 through an inlet line 212 and selectively delivers engine oil from such source to the cylinder 234 through a supply line 238. Excess oil from the solenoid 206 is drained to a sump 236 by way of a line 210.
  • the cylinder 234 may be mounted at an exposed end of the camshaft 126 so that the piston 234a bears against an exposed free end 200c of the spool 200.
  • the solenoid 206 is preferably mounted in a housing 234b which also houses the cylinder 234a.
  • the control system of Figure 19 is capable of operating independently of variations in the viscosity or pressure of the hydraulic system.
  • the centered or null position of the spool 200 is the position where no change in camshaft to crankshaft phase angle is occurring, and it is important to be able to rapidly and reliably position the spool 200 in its null position for proper operation of a VCT system.
  • Make-up oil for the recesses 132a, 132b of the sprocket 132 to compensate for leakage therefrom is provided by way of a small, internal passage 220 within the spool 200, from the passage 198a to an annular space 198b of the cylindrical member 198, from which it can flow into the inlet line 182.
  • a check valve 222 is positioned within the passage 220 to block the flow of oil from the annular space 198b to the portion 198a of the cylindrical member 198.
  • the vane 160 is alternatingly urged in clockwise and counterclockwise directions by the torque pulsations in the camshaft 126 and these torque pulsations tend to oscillate the vane 160, and, thus, the camshaft 126, relative to the sprocket 132.
  • such oscillation is prevented by the hydraulic fluid within the recesses 132a, 132b of the sprocket 132 on opposite sides of the lobes 160a, 160b, respectively, of the vane 160, because no hydraulic fluid can leave either of the recesses 132a, 132b, since both return lines 194, 196 are blocked by the position of the spool 200, in the Figure 19 condition of the system.
  • the periphery of the vane 160 has an open oil passage slot, element 160c in Figures 10, 11, 15, 16 and 17, which permits the transfer of oil between the portion of the recess 132a on the right side of the lobe 160a and the portion of the recess 132b on the right side of the lobe 160b, which are the non-active sides of the lobes 160a, 160b; thus, counterclockwise movement of the vane 160 relative to the sprocket 132 will occur when flow is permitted through return line 194 and clockwise movement will occur when flow is permitted through return line 196.
  • the passage 182 is provided with an extension 182a to the non-active side of one of the lobes 160a, 160b, shown as the lobe 160b, to permit a continuous supply of make-up oil to the non-active sides of the lobes 160a, 160b for better rotational balance, improved damping of vane motion, and improved lubrication of the bearing surfaces of the vane 160.
  • the supply of make-up oil in this manner avoids the need to route the make-up oil through the solenoid 206.
  • the flow of make-up oil does not affect, and is not affected by, the operation of the solenoid 206.
  • make-up oil will continue to be provided to the lobes 160a, 160b in the event of a failure of the solenoid 206, and it reduces the oil flow rates that need to be handled by the solenoid 206.
  • Figures 10-18 which correspond to the elements of Figure 19, as described above, are identified in Figures 10-18 by the reference numerals which were used in Figure 19, it being noted that the check valves 184 and 186 are disc-type check valves in Figures 10-18 as opposed to the ball type check valves of Figure 19. While disc-type check valves are preferred for the embodiment of Figures 10-18, it is to be understood that other types of check valves can also be used.
  • Figure 20 illustrates a modification of the embodiment of Figures 10-18.
  • the elements of Figure 20 which correspond in structure and function to the elements of Figures 10-18 are identified by a 300 series or a 400 series numeral, the last two digits of which correspond to the last two digits of the embodiment of Figures 10-18.
  • the piston 434a is not aligned with the spool 400 and is incapable of bearing against its exposed free end 400c. Rather, the piston 434a acts against an end 440a of a lever arm 440, an opposite end 440b of which bears on the free end 400c of the spool.
  • the lever arm 440 is pivoted at a location 440c between its ends, for example at a location on the engine block or on a housing attached thereto, to function as a first class lever.
  • the embodiment of Figure 20, thus, is somewhat shorter in axial length, along the axis of the associated camshaft, and this is an advantage in adapting the variable camshaft timing system of the present invention to some vehicle/engine configurations.
  • Figure 21 schematically illustrates a modification of the arrangement of Figure 19.
  • the elements of Figure 21 which correspond in structure and function to the elements of Figure 19 are identified by a 500 series numeral or a 600 series numeral, the last two digits of which correspond to the last two digits of the embodiment of Figure 19.
  • a spool valve 592 which is actually an extension of a camshaft 526. In this way all applicable hydraulic fluids are kept within the camshaft 526. This arrangement minimizes the required external dimensional requirements relative to those of other embodiments of the invention, and this is especially important in engine and vehicle configurations wherein space within an engine compartment longitudinally of the camshaft is particularly limited.
  • the spool valve 592 is made up of a cylindrical portion 598 of the camshaft 526 and a spool 600 which is slidable to and fro within the portion 598.
  • the spool 600 has cylindrical lands 600a and 600b on opposed ends thereof, and the lands 600a and 600b, which fit snugly within the portion 598, are positioned so that the land 600b will block the exit of hydraulic fluid from the return line 596, or the land 600a will block the exit of hydraulic fluid from the return line 594, or the lands 600a and 600b will block the exit of hydraulic fluid from both the return lines 594 and 596, as is shown in Figure 21, where the camshaft 526 is being maintained in a selected intermediate position relative to the crankshaft of the associated engine.
  • the position of the spool 600 within the member 598 is influenced by an opposed pair of springs 602, 604 which act on the ends of the lands 600a, 600b, respectively.
  • the spring 602 resiliently urges the spool 600 to the left, in the orientation illustrated in Figure 21, and the spring 604 resiliently urges the spool 600 to the right in such orientation.
  • the position of the spool 600 within the portion 598 is further influenced by a supply of pressurized hydraulic fluid within a subportion 598a of the portion 598, on the outside of the land 600a, which urges the spool 600 to the left.
  • the subportion 598a of the portion 598 receives its pressurized fluid (engine oil) directly from the main oil gallery ("MOG") 630 of the engine by way of a conduit 630a, and this oil is also used to lubricate a bearing 632 in which the camshaft 526 of the engine rotates.
  • engine oil pressurized fluid
  • MOG main oil gallery
  • the hydraulic fluid within the subportion 598a acts on the end of the land 600a of the spool 600 to urge the spool 600 to the left, in the configuration illustrated in Figure 21.
  • the hydraulic fluid within the subportion 598a is permitted to bleed into an otherwise closed, interior portion 526a of the camshaft 526 where it acts on a surface 600e of a transversely extending portion 600f of an extension 600g of the spool 600. Since the exposed surface area of the surface 600e is greater than the exposed surface area of the end of the land 600a, the net effect of the hydraulic fluid entering the subportion 598a from the main oil gallery 630 is to urge the spool 600 to the right in the Figure 21 configuration.
  • the hydraulic pressure within the portion 526e is controlled by a solenoid 606, preferably of the pulse width modulated type (PWM), in response to a control signal from an electronic engine control unit (ECU) 608, shown schematically, which may be of conventional construction.
  • a solenoid 606 preferably of the pulse width modulated type (PWM)
  • ECU electronic engine control unit
  • the on-off pulses of the solenoid 606 will be of equal duration; by increasing or decreasing the on duration relative to the off duration, the pressure in the portion 526e will be increased or decreased relative to such predetermined ratio, thereby moving the spool 600 to the left or to the right, respectively.
  • the solenoid 606 receives engine oil from the engine oil gallery 630 through an inlet line 612 and selectively delivers engine oil from such sources to the portion 526e through a supply line 638. Excess oil from the solenoid 606 is drained to a sump 636 by way of a line 610.
  • the embodiment of Figure 21 is also especially well suited for use in a belt driven variable camshaft timing system, because it is usually highly desirable that the belts and pulleys and other belt contacting elements in such a system be operated in a dry, unlubricated condition. This is relatively easy to accomplish with the embodiment of Figure 21 because all hydraulic fluids are maintained within the interior of the camshaft 526, thereby eliminating the need for complex sealing arrangements at an end thereof.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Valve Device For Special Equipments (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
EP92304883A 1991-06-11 1992-05-29 Differential pressure control system for variable camshaft timing system Expired - Lifetime EP0518528B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US07/713,465 US5107804A (en) 1989-10-16 1991-06-11 Variable camshaft timing for internal combustion engine
US763514 1991-09-20
US07/763,514 US5172659A (en) 1989-10-16 1991-09-20 Differential pressure control system for variable camshaft timing system
US713465 1991-09-20

Publications (2)

Publication Number Publication Date
EP0518528A1 EP0518528A1 (en) 1992-12-16
EP0518528B1 true EP0518528B1 (en) 1995-10-11

Family

ID=27109003

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92304883A Expired - Lifetime EP0518528B1 (en) 1991-06-11 1992-05-29 Differential pressure control system for variable camshaft timing system

Country Status (5)

Country Link
US (1) US5172659A (ja)
EP (1) EP0518528B1 (ja)
JP (1) JP3333234B2 (ja)
CA (1) CA2069041C (ja)
DE (1) DE69205339T2 (ja)

Families Citing this family (79)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4116169A1 (de) * 1991-05-17 1992-11-19 Bosch Gmbh Robert Vorrichtung zur verstellung der drehwinkelzuordnung einer nockenwelle zu ihrem antriebselement
US5218935A (en) * 1992-09-03 1993-06-15 Borg-Warner Automotive Transmission & Engine Components Corporation VCT system having closed loop control employing spool valve actuated by a stepper motor
US5497738A (en) * 1992-09-03 1996-03-12 Borg-Warner Automotive, Inc. VCT control with a direct electromechanical actuator
US5291860A (en) * 1993-03-04 1994-03-08 Borg-Warner Automotive, Inc. VCT system with control valve bias at low pressures and unbiased control at normal operating pressures
DE4415524B4 (de) * 1993-05-03 2005-02-24 Borgwarner Inc., Sterling Heights Ventilsteuersystem für eine Brennkraftmaschine
US5367992A (en) * 1993-07-26 1994-11-29 Borg-Warner Automotive, Inc. Variable camshaft timing system for improved operation during low hydraulic fluid pressure
JPH07238806A (ja) * 1994-02-25 1995-09-12 Ofic Co 可変バルブタイミング装置
JP3820478B2 (ja) * 1994-05-13 2006-09-13 株式会社デンソー ベーン式回転位相調節装置
US5657725A (en) * 1994-09-15 1997-08-19 Borg-Warner Automotive, Inc. VCT system utilizing engine oil pressure for actuation
US6006709A (en) * 1995-06-14 1999-12-28 Nippondenso Co., Ltd. Control apparatus for varying a rotational or angular phase between two rotational shafts, preferably applicable to a valve timing control apparatus for an internal combustion engine
GB2302391B (en) * 1995-06-14 1999-08-18 Nippon Denso Co Control apparatus for varying the rotational or angular phase between two rotational shafts
DE69601916T3 (de) * 1995-11-30 2003-04-24 Aisin Seiki K.K., Kariya Brennkraftmaschine mit einer Ventilzeitsteuerungsvorrichtung
JP3262207B2 (ja) * 1996-10-02 2002-03-04 株式会社デンソー 内燃機関用バルブタイミング調整装置
JP3620684B2 (ja) * 1997-01-31 2005-02-16 株式会社デンソー 内燃機関用バルブタイミング調整装置
DE19905646A1 (de) * 1999-02-11 2000-08-17 Schaeffler Waelzlager Ohg Nockenwellenstellvorrichtung und Steuerventil mit Leckageausgleich
DE50109814D1 (de) * 2000-03-02 2006-06-22 Siemens Ag Verfahren zur steuerung eines stellglieds mittels des halte-tast-verhältnisses
EP1272741B1 (de) 2000-04-14 2004-08-04 Siemens Aktiengesellschaft Verfahren zur regelung eines stellgliedes
US6561146B2 (en) 2001-07-25 2003-05-13 Borgwarner, Inc. Method of controlling resonances in internal combustion engine having variable cam timing
US20030033998A1 (en) 2001-08-14 2003-02-20 Marty Gardner Hybrid multi-position cam indexer having controls located in rotor
US6763791B2 (en) * 2001-08-14 2004-07-20 Borgwarner Inc. Cam phaser for engines having two check valves in rotor between chambers and spool valve
ATE309455T1 (de) * 2002-03-18 2005-11-15 Gasdynamische druckwellenmaschine
US6745735B2 (en) 2002-04-19 2004-06-08 Borgwarner Inc. Air venting mechanism for variable camshaft timing devices
US6866013B2 (en) * 2002-04-19 2005-03-15 Borgwarner Inc. Hydraulic cushioning of a variable valve timing mechanism
US6666181B2 (en) 2002-04-19 2003-12-23 Borgwarner Inc. Hydraulic detent for a variable camshaft timing device
US6883475B2 (en) 2002-04-22 2005-04-26 Borgwarner Inc. Phaser mounted DPCS (differential pressure control system) to reduce axial length of the engine
US6792902B2 (en) * 2002-04-22 2004-09-21 Borgwarner Inc. Externally mounted DPCS (differential pressure control system) with position sensor control to reduce frictional and magnetic hysteresis
US6729283B2 (en) 2002-04-22 2004-05-04 Borgwarner Inc. Externally mounted vacuum controlled actuator with position sensor control means to reduce functional and magnetic hysteresis
US6571757B1 (en) 2002-04-22 2003-06-03 Borgwarner Inc. Variable force solenoid with spool position feedback to control the position of a center mounted spool valve to control the phase angle of cam mounted phaser
US6622675B1 (en) * 2002-04-22 2003-09-23 Borgwarner Inc. Dual PWM control of a center mounted spool value to control a cam phaser
US6779501B2 (en) * 2002-06-14 2004-08-24 Borgwarner Inc. Method to reduce rotational oscillation of a vane style phaser with a center mounted spool valve
US6938592B2 (en) * 2002-06-17 2005-09-06 Borgwarner Inc. Control method for electro-hydraulic control valves over temperature range
US7021257B2 (en) * 2002-06-17 2006-04-04 Borgwarner, Inc. Compensating for VCT phase error over speed range
US6810843B2 (en) 2002-06-17 2004-11-02 Borgwarner Inc. Control method for achieving expected VCT actuation rate using set point rate limiter
US6745732B2 (en) 2002-06-17 2004-06-08 Borgwarner Inc. VCT cam timing system utilizing calculation of intake phase for dual dependent cams
US6766776B2 (en) 2002-06-17 2004-07-27 Borgwarner Inc. Control method for preventing integrator wind-up when operating VCT at or near its physical stops
US6840202B2 (en) * 2002-09-03 2005-01-11 Borgwarner Inc. Method to reduce noise of a cam phaser by controlling the position of center mounted spool valve
US6668778B1 (en) 2002-09-13 2003-12-30 Borgwarner Inc. Using differential pressure control system for VCT lock
US6814038B2 (en) * 2002-09-19 2004-11-09 Borgwarner, Inc. Spool valve controlled VCT locking pin release mechanism
US6941913B2 (en) * 2002-09-19 2005-09-13 Borgwarner Inc. Spool valve controlled VCT locking pin release mechanism
US6883479B2 (en) * 2002-11-04 2005-04-26 Borgwarner Inc. VCT phaser having an electromagnetic lock system for shift and lock operation
US6932037B2 (en) * 2003-01-28 2005-08-23 Borgwarner Inc. Variable CAM timing (VCT) system having modifications to increase CAM torsionals for engines having limited inherent torsionals
US6772721B1 (en) 2003-06-11 2004-08-10 Borgwarner Inc. Torsional assist cam phaser for cam in block engines
US20050005886A1 (en) * 2003-07-10 2005-01-13 Borgwarner Inc. Method for reducing VCT low speed closed loop excessive response time
US6932033B2 (en) * 2003-07-10 2005-08-23 Borgwarner Inc. System and method for improving VCT closed-loop response at low cam torque frequency
US7214153B2 (en) * 2003-07-18 2007-05-08 Borgwarner Inc. Method of changing the duty cycle frequency of a PWM solenoid on a CAM phaser to increase compliance in a timing drive
US20050028770A1 (en) * 2003-08-04 2005-02-10 Borgwarner Inc. Cam position measurement for embedded control VCT systems using non-ideal pulse-wheels for cam position measurement
US20050045130A1 (en) * 2003-08-27 2005-03-03 Borgwarner Inc. Camshaft incorporating variable camshaft timing phaser rotor
US20050045128A1 (en) * 2003-08-27 2005-03-03 Borgwarner Inc. Camshaft incorporating variable camshaft timing phaser rotor
US7231896B2 (en) * 2003-10-10 2007-06-19 Borgwarner Inc. Control mechanism for cam phaser
US20050076868A1 (en) * 2003-10-10 2005-04-14 Borgwarner Inc. Control mechanism for cam phaser
US6941799B2 (en) * 2003-10-20 2005-09-13 Borgwarner Inc. Real-time control system and method of using same
US6955145B1 (en) * 2004-04-15 2005-10-18 Borgwarner Inc. Methods and apparatus for receiving excessive inputs in a VCT system
US7000580B1 (en) 2004-09-28 2006-02-21 Borgwarner Inc. Control valves with integrated check valves
EP1650411A1 (de) * 2004-10-19 2006-04-26 Ford Global Technologies, LLC, A subsidary of Ford Motor Company Nockenwellenversteller und Verfahren zur Veränderung der Nockenwellenphase mittels einem künstlichen Muskel
US6971354B1 (en) 2004-12-20 2005-12-06 Borgwarner Inc. Variable camshaft timing system with remotely located control system
WO2006119463A1 (en) * 2005-05-02 2006-11-09 Borgwarner Inc Timing phaser control system
WO2006119210A2 (en) * 2005-05-02 2006-11-09 Borgwarner Inc Timing phaser with offset spool valve
JP2007146830A (ja) * 2005-10-31 2007-06-14 Hitachi Ltd 内燃機関の油圧制御装置
GB2432645B (en) * 2005-11-28 2010-12-29 Mechadyne Plc Variable phase drive coupling
US7318401B2 (en) * 2006-03-15 2008-01-15 Borgwarner Inc. Variable chamber volume phaser
US7240651B1 (en) 2006-03-30 2007-07-10 Ford Global Technologies, Llc Variable cam timing damper
DE602007006491D1 (de) 2006-07-07 2010-06-24 Borgwarner Inc Steuerverfahren für ein antriebssystem mit variabler verdichtung
WO2008042622A1 (en) * 2006-09-29 2008-04-10 Borgwarner Inc Variable event duration reduction (vedr) cam phaser
WO2008140897A1 (en) * 2007-05-14 2008-11-20 Borgwarner Inc. Cam mounted accumulator
WO2008157076A1 (en) * 2007-06-19 2008-12-24 Borgwarner Inc. Concentric cam with phaser
EP2171222B1 (en) * 2007-07-02 2017-11-29 BorgWarner Inc. Concentric cam with check valves in the spool for a phaser
JP4492684B2 (ja) * 2007-11-28 2010-06-30 株式会社デンソー バルブタイミング調整装置
JP2009138611A (ja) * 2007-12-05 2009-06-25 Denso Corp バルブタイミング調整装置
US8291876B2 (en) * 2008-01-29 2012-10-23 Comptetition Cams Inc. Camshaft variable timing limiting devices, methods of assembly, and uses thereof
JP5126157B2 (ja) * 2009-04-23 2013-01-23 株式会社デンソー 内燃機関の可変バルブタイミング制御装置
JP5136628B2 (ja) * 2010-01-20 2013-02-06 株式会社デンソー バルブタイミング調整装置
JP2013524092A (ja) 2010-04-06 2013-06-17 ボーグワーナー インコーポレーテッド 同心カムシャフトに沿って中央に配置したカム位相器
US8984853B2 (en) 2010-05-21 2015-03-24 United Technologies Corporation Accessing a valve assembly of a turbomachine
US9080473B2 (en) 2010-11-02 2015-07-14 Borgwarner, Inc. Cam torque actuated—torsional assist phaser
WO2012061233A2 (en) 2010-11-02 2012-05-10 Borgwarner Inc. Cam torque actuated phaser with mid position lock
WO2014099374A1 (en) * 2012-12-21 2014-06-26 Borgwarner Inc. Variable compression ratio piston system
US9810106B2 (en) 2014-03-13 2017-11-07 Delphi Technologies, Inc. Camshaft phaser
US9528399B2 (en) * 2014-10-21 2016-12-27 Ford Global Technologies, Llc Method and system for variable cam timing device
US9410453B2 (en) 2014-10-21 2016-08-09 Ford Global Technologies, Llc Method and system for variable cam timing device

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1152959B (it) * 1982-05-17 1987-01-14 Alfa Romeo Spa Dispositivo per la variazione automatica della fasatura di un albero a camme
JP2613875B2 (ja) * 1986-11-21 1997-05-28 株式会社ユニシアジェックス 内燃機関のバルブタイミング制御装置
JPH0192504A (ja) * 1987-09-30 1989-04-11 Aisin Seiki Co Ltd 弁開閉時期制御装置
GB2217812A (en) * 1988-04-30 1989-11-01 Ford Motor Co Variable camshaft phasing mechanism
IT1217500B (it) * 1988-05-05 1990-03-22 Alfa Lancia Ind Dispositivo per la variazione automatica della fasatura per un motore a c.i.
DE3825074C1 (ja) * 1988-07-23 1989-10-19 Daimler-Benz Aktiengesellschaft, 7000 Stuttgart, De
JPH0727365Y2 (ja) * 1988-08-18 1995-06-21 株式会社ユニシアジェックス 内燃機関のバルブタイミング制御装置
FR2641832B1 (fr) * 1989-01-13 1991-04-12 Melchior Jean Accouplement pour la transmission de couples alternes
DE3930157A1 (de) * 1989-09-09 1991-03-21 Bosch Gmbh Robert Einrichtung zur verstellung der drehwinkelzuordnung einer nockenwelle zu ihrem antriebselement
US5058539A (en) * 1989-09-20 1991-10-22 Atsugi Unisia Corporation Valve timing adjusting system for internal combustion engine
US5107804A (en) * 1989-10-16 1992-04-28 Borg-Warner Automotive Transmission & Engine Components Corporation Variable camshaft timing for internal combustion engine
US5046460A (en) * 1989-10-16 1991-09-10 Borg-Warner Automotive Transmission & Engine Components Corporation Variable camshaft timing for internal combustion engine
US5002023A (en) * 1989-10-16 1991-03-26 Borg-Warner Automotive, Inc. Variable camshaft timing for internal combustion engine
US5088456A (en) * 1990-01-30 1992-02-18 Atsugi-Unisia Corporation Valve timing control system to adjust phase relationship between maximum, intermediate, and minimum advance position

Also Published As

Publication number Publication date
DE69205339T2 (de) 1996-03-28
CA2069041C (en) 2003-12-02
CA2069041A1 (en) 1992-12-12
DE69205339D1 (de) 1995-11-16
EP0518528A1 (en) 1992-12-16
US5172659A (en) 1992-12-22
JP3333234B2 (ja) 2002-10-15
JPH05195726A (ja) 1993-08-03

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